The present disclosure relates to earth-penetrating drill bits and, more particularly, to fixed-cutter rotating drill bits used for drilling oil and gas wells.
Wellbores for the oil and gas industry are commonly drilled by a process of rotary drilling. In conventional vertical drilling a drill bit is mounted on the end of a drill string (i.e., drill pipe plus drill collars, etc.), which may be several miles long. At the surface of the well, a rotary drive turns the drill string, including the drill bit arranged at the bottom of the hole, while drilling fluid (or “mud”) is pumped through the drill string. In other drilling operations, the drill bit may be rotated using a mud motor arranged axially adjacent the drill bit in the downhole environment and powered using the mud circulated from the surface.
When the drill bit wears out or breaks during drilling, it must be brought up out of the hole. This requires “tripping” the drill string out of the wellbore, which typically involves a heavy hoist pulling the entire drill string out of the hole in stages of, for example, about ninety feet of drill pipe at a time. Since the drill string may extend tens of thousands of feet into the earth, one tripping job can be quite time-consuming and expensive. To resume drilling, a new or refurbished drill bit is attached to the end of the drill pipe and subsequently lowered into the wellbore, and the foregoing process is then reversed until the bit reaches the bottom of the well and drilling can recommence. As can be appreciated, in order to minimize round trips for bit replacement during drilling, the durability and robustness of drill bits are very important features.